Continuous drawing bench

ABSTRACT

Bench for drawing elongated material through a die comprises a plurality of carriages, each carrying a pair of jaws for gripping the material, and crank and connecting rod means for actuating said carriages to successively advance the material through the die.

United States Patent 1191 Peytavin Oct. 29, 1974 CONTINUOUS DRAWING BENCH 967,178 8/1910 Edison et al. 72/290 1 1 Peywin, Nwmy-sur-Seine, 322131? 211353 itifrgiiiiiiiiiiii111111111113113131: iii/ 2i France 2,723,117 11/1955 Clark et al. 226/164 lAssigneez Anmymedite: v u 3,487,988 GOOdWln Usines a tubes de Lorraine-Escaut et Vallourec Reunies), Paris, France Primary w Lanham [22] Filed: Jam 24, 1973 Assistant Examiner-James Duz an Attorney, Agent, or Firm-Br1sebo1s & Kruger [2l] Appl. No.: 326,236

[30] Foreign Application Priority Data .Ian. 25, 1972 France .1211233? [57] ABSTRACT U-S. Ben h for drawing elongated material through a 226/112 226/164 comprises a plurality of carriages, each carrying a pair Cl. f jaws fo the material and crank and con- Field of Search 72/287, 233, 289, necting rod means for actuating said carriages to sue- 72/291; 226/112 163 cessively advance the material through the die.

[56] References Cited UNITED STATES PATENTS 293,167 2/l884 l-laas 72/290 7 Chums 8 mawmg F'gures PATENTEBBBI 291974 w J\ \\\\\/\L m w. w

1 /J V. q m" Q a 1 1 v l I I f] wk 1 z 1 MN T 9 MI! k 1T1, W m nu N m NM WW5 w CONTINUOUS DRAWING BENCH SUMMARY OF THE INVENTION This invention relates to a continuous drawing bench. Continuous drawing benches are machines for drawing a product such as a wire or a rod through a die to calibrate the section of the product and straighten it. They make it possible to exert traction on the product as it passes through the die without interruption. Before entering the drawing bench the wire or like product is generally wound up in a coil of substantial length. At the output of the machine the product is cut into sections of predetermined length.

There is a known type of drawing bench comprising two pairs of gripping jaws positioned successively with respect to the drawing direction, each pair of jaws gripping the wire successively to advance it for a certain distance, while the other pair of jaws travels through the same distance in the opposite direction to grip the wire closer to the die.

The pairs of jaws are supported on carriages which slide on slideways mounted on the framework of the machine, each carriage having its movement controlled by a cam on a drum which rotates about an axis of rotation parallel to the direction in which the wire is drawn.

Taking into account the substantial tractive force required, the drum carrying the cams must be rather large, even though the carriages are not advanced over a very long path of travel. This makes it necessary to have a rather high frequency of reciprocation of the carriages in order to have a high enough drawing speed. This results in parasitic forces due to the substantial inertia which forces are supported by the cams and limit the maximum drawing speed to about 60 meters a minute.

Moreover, known machines do not have all the robustnes's desirable, especially when they must be operated near the maximum speed for which they have been constructed.

The present invention relates to a drawing bench in which the movement of the jaws is controlled solely by rotating pivoted members. This results in a mechanically simplified construction and leads to the possibility of operating the drawing bench according to the invention at a speed substantially higher than those of benches heretofore known.

Moreover, the construction of the drawing benches according to the invention utilizes components made on a large scale as ordinary articles of commerce, such as roller bearings and universal joints, thus avoiding the long and expensive machining processes heretofore necessary to manufacture the cam-carrying drums in the prior art machines.

It is an object of the present invention to provide as a new article'of manufacture a drawing bench for wire, rods, or the like, of the type in which the product is drawn through the die by being successively gripped between a plurality of pairs of jaws, each mounted on a carriage which is slidable on the framework of the machine parallel to the direction of drawing, and which is characterized by the fact that each carriage is displaced by a crank and connecting rod system, all of the cranks which actuate the carriages being driven in synchronism but at an angular distance from each other such that at each instant the cranks are regularly angularly distributed.

In a preferred embodiment of the invention three jaw-carrying carriages are used, which are controlled by cranks angularly spaced at In this preferred embodiment of the invention means are used conjointly with the crank and connecting rod system means which make it possible to impart to each carriage a constant or substantially constant linear speed during the portion of its movement during which it exerts traction on the product to be drawn.

A particularly advantageous means for this purpose consists of a universal joint which is positioned between the shaft supporting the crank and the shaft which drives this crank with an angular spacing between the two shafts of the universal joint.

In another embodiment of the invention, the crank may be driven at a constant angular speed and a linear displacement to the carriage during a part of its course because of the fact that the connecting rod connecting the carriage to the crank is made in two parts pivoted at a common point which is itself connected by a connecting rod to another crank rotating in synchronism with the first one.

This has a knee-joint effect on the connecting rod which controls the carriage so that the useful length of the connecting rod is so varied as to correct the variations in speed which are communicated to the carriage by a conventional crank and connecting rod motion.

In an improved embodiment of the invention the angular displacement of the connecting rod with respect to the carriage which it drives is used to insure automatic control of the opening and closing of the jaws which grip the product to be drawn.

According to this improved embodiment a crank may then be used which is fixed to the connecting rod and positioned at a point at which this connecting rod is pivotally attached to the carriage so as to control the movements of the jaws with respect to the carriage through a linkage system.

In order to limit the travel of the jaws to the distance which is useful in gripping and releasing the product to be drawn, the linkage used advantageously comprises a composite link positioned between two articulated levers which may be elastically elongated by compression of a spring, and one of the ends of which is axially slidable at its point of attachment to one of the levers so that said lever may freely assume a position which, at certain moments, corresponds to the minimum length of the composite link.

This articulation may be easily provided by providing on the end of the connecting rod a stop situated beyond the point of attachment to the oscillating lever inside which the rod must slide and pivot.

In order that the invention may be better understood, one embodiment thereof will now be described, purely by way of illustration and example, with reference to the accompanying drawings on which:

FIG. 1 is a schematic perspective view of a device for driving a carriage according to the invention;

FIG. 2 is a schematic longitudinal sectional view through a drawing bench according to the invention;

FIG. 3 is a sectional view on a larger scale taken through the bench of FIG. 2;

FIGS. 4-7 are schematic views representing the four stages of operation of the control for the jaws in the apparatus according to the invention; and

FIG. 8 is a diagram representing the displacement of the carriage as a function of the angular position of the constant speed shaft which drives the crank through a universal joint.

The framework 1 carries at its upper part three carriages 2 slidable in slideways schematically represented on FIG. 2. Each carriage 2 is connected at 3 to one end of a connecting rod 4 the other end of which is pivotally connected to a crank 6 which is rotated about a shaft 7. The three cranks 6 are angularly spaced 120 from each other, that is to say, the cranks are regularly angularly spaced. A frame 8 is schematically shown at the left of FIG. 2 and supports the dies through which the wire 9 which is to be drawn must pass.

FIG. 1 schematically shows the various components which are necessary to control a single carriage 2, including the crank 6 pivotally attached at to the connecting rod 4, which is pivotally attached at 3 to the carriage 2. The figureclearly shows the slideway 10 on which the carriage 2 travels. FIG. 1 also shows how the jaws 11 and 11' are mounted on the carriage in a conventional manner. These jaws have a sufficient length to be able to grip the wire 9 which is to be drawn without exerting thereon a pressure so great as to risk deforming the product which is to be drawn. They have in a conventional manner a trapezoidal section to assure their closing when they move toward the left with respect to thecarriage 2 (as shown in FIG. 1).

Balls or rollers are positioned between the lateral sides of the jaws and their mounting on the carriage so as to permit relative sliding at low friction, which insures reliable, easy gripping and release of the jaws.

It will be appreciated that, under these conditions, when the carriage 2 is driven in the drawing direction (which is represented by the arrow F on FIG. 1), the frictional effect of the wire 9 on the jaws 11 and 11' has a tendency to shift them toward the left with respect to the carriage and thus accentuate the gripping action.

This self-gripping effect on the jaws in itself assures a good grip on the wire in the jaws from the time the latter are engaged in their gripping position.

It will also be appreciated that, from the time the carriage 2 is longitudinally driven with a speed less than that of the wire 9, the jaws l1 and 11' which continue to be driven at the same speed as the wire 9 have a tendency to release their grip.

FIG. 1 shows the universal joint 12 through which the crank 6 is rotatably driven from a shaft 13 through reduction gearing 14. The shaft 13 simultaneously drives the three cranks 6- through three reduction gears 14 and three universal joints 12. Each universal joint occupies the same angular position with respect to the crank 6 which it controls.

It will hereinafter be explained how the universal joint 12 may modify the angular speed of the crank 6 so as to produce a constant speed of the carriage during its working stroke.

FIG. I shows schematically how the device according to the invention assures the automatic control of the opening and closing of the jaws 11 and 11'. For this purpose a crankpin 15 fixed to the connecting rod 4 is pivotally attached at 16 to a composite link 17, the other end of which is mounted at 18 on the end of a lever 19, which lever 19 oscillates about a central point 20. The other end 21 of the lever 19 is connected to two rods 22 and 22' pivotally attached at 23 and 23' to the jaws l1 and 11'.

' As schematically shown on FIG. 4 the composite link 17 comprises a rod 24 slidable inside a cylinder 25 which is itself pivotally attached at 16 to the crankpin 15. The rod 24 carries at its right end a piston 26 which slides in the cylinder 25 and is constantly urged toward the bottom of the cylinder by a compression spring 27.

The rod 24 is slidable and pivotable in its mounting 18 on the swinging lever 19. As may be seen on FIG. 1, the rod 24 has at one end a stop 28 which bears at 18 on the lever 19 when the angular motion of the crankpin draws the point 16 to the right.

FIG. 3 shows on a larger scale the different components which have just been described. As may be seen on this Figure, the principal axes of rotation or pivotal motion are mounted in ball or roller bearings which insure a great accuracy in the drive and permit a high speed of rotation and consequently high speed drawing of the wire being drawn.

FIGS. 4-7 show four consecutive phases in the movement of a carriage.

In the position shown in FIG. 4 the carriage, which has a speed substantially equal to the speed of the wire, (which is at this point, driven by anothercarriage) is in the process of automatically closing its jaw to grip the wire in order to drive it while the carriage which is actually drawing the wire returns to the rear.

For this purpose the crank 6 reaches an angular position at which it moves the point 16 on the crankpin 15 toward the right into a position such that the stop 28 on the rod 24 bears on the swinging lever 19.

As the spring 27 is precompressed, all subsequent movement of the crank 6 results in movement of the point 16 to the right and, through the composite link 17, in swinging the lever 19 about the point 20 so as to displace the jaws 11 and 11' toward the left by means of the rods 22 and 22'.

This displacement of the jaws 11 and 11' toward the left is accompanied by their gripping of the wire 9. R0- tation of the crank 6 from the position shownon FIG. 4 thus insures driving of the wire 9 by progressive gripping of the jaws 11 and 11 because the point 16 continues to move toward the right while compressing the spring 27 which thus increases the tractive force exerted on the rods 22, and consequently the traction exerted by the jaws on the wire 9.

FIG. 5 shows an intermediate step in which the composite link 17 is elongated by compression of the spring 27, which insures a gripping pressure on the jaws and at the same time permits the crank 6 to pass to a vertical position which corresponds to the maximum displacement of the point 16 to the right.

FIG. 6 shows the position of the different parts at the moment at which the carriage is about to release the wire. In this position, the point 16 at the end of the crank pin 15 is sufficiently displaced to the left in the direction of the carriage for the spring 27 to have completely depressed the piston 26 into the bottom of the cylinder. The stop 28 on the rod 24 still abuts against the swinging lever 19.

From this position, the jaws automatically open and release the wire 9, which will thereafter be advanced by another pair of jaws. In effect, from this moment, the spring 25 no longer exerts a force toward the left to insure gripping of the wire by the jaws. The wire nevertheless continues to be drawn at the same speed by another pair of jaws while the carriage shown on FIG. 6

slows down and then reverses its direction of movement.

Moreover, after the position shown on FIG. 6, the stop 28 of the rod 24 moves to the left, which automatically permits a slight movement toward the right of the jaws relative to the carriage.

The releasing and opening movement of the jaws takes place automatically because the jaws which are driven at the same speed as the wire have, as a consequence of their own inertia, a tendency to move to the right with respect to the carriage because the latter is braked to damp its return movement toward the left.

Moreover the friction of the wire on the jaws also has a tendency to drive them toward the right.

FIG. 7 shows a position during thereturn of the carriage toward the left. In this position the jaws have been opened and the stop 28 of the rod 24 is spaced from the pivotal lever I9. After rotation through about a half a turn, the parts regain the position shown on FIG. 4.

It will thus be seen that, according to this embodiment of the invention, an automatic control of the closing and opening of the jaws which grip the wire to drive it during the forward movement of the carriage is simply and automatically obtained.

FIG. 8 is a diagram showing along the ordinate the movements of the carriage as a function of the angular position of the shaft of the reducing gear 14 which is connected to the universal joint 12, and which is shown along the abscissa.

However, since the shaft 13 which drives the reducing gear is at a constant speed, the abscissa can represent either the angle of rotation of the reduction gear or time. It will be noted that at 140 of rotation (from the graduation ID to the graduation 150) the displacement of the carriage is linear as a function of time, which corresponds to a constant speed which is that at which the wire 9 is driven.

This result is obtained as a consequence of the fact that the shaft driven by the universal joint, which is driven by its own driving shaft at a constant speed, un-

dergoes alternatively accelerations and decelerations with respect to the driving shaft. In the present case the arrangement of the universal joint is such that the driven shaft undergoes an acceleration in the lower part of the straight line which represents the displacement of the carriage and a deceleration in the upper part of this straight line.

In the embodiment, the curve of which is represented on FIG. 8, the different components have the following characteristics:

Length of crank 6 350 mm Length of connecting rod 4 875 mm (which is 2.5

times the length of the crank) The sliding movement of the pivotal connection 3 on the carriage takes place along a straight line which is at a distance of 280 mm from the axis of rotation 7 of the crank (which is 0.8 times the length of the crank) The universal joint I2 has an angular deviation of 45 The curve of FIG. 8 shows the beginning of the traction of a wire by a carriage as the point I and the end of this traction by the point II.

The points IV, V, VI and VII correspond respectively to the positions represented on FIGS. 4-7.

It will be seen from an examination of the curve that at the moment at which the jaws effectively grip the wire at point I, the carriage already has a speed substantially equal to the speed of the wire. In like manner at point II at which the jaws release the wire, the carriage continues to advance at a speed which is still equal to the speed of the wire. Under these conditions a grip and release of the wire by the jaws is obtained without any sliding between the wire and the jaws, which avoids any risk of injury to the product being drawn.

FIG. 8 also shows that the speed of the carriage decreases quite rapidly after the point II (to be reversed at the point VII), which creates a relative speed between the carriage and the jaws which facilitates or causes their opening.

At the same time, when, before the point IV, the carriage regains the speed of the wire, this is done progressively and the components regain without abruptness the position shown on FIG. 4.

It will be seen that, as a consequence of the invention, it is possible to produce a continuous drawing bench in which the product being drawn is driven by a perfectly regular movement without utilizing cams, the bench according to the invention being of a simple construction relying solely on pivotal connections.

It will of course be appreciated that the embodiment which has been described has been given purely by way of illustration and example and may be modified as to.

detail without thereby departing from the basic principles of the invention. In particular, it is obvious that it is not limited to the case in which three carriages are used to advance the wire. In like manner, the means of controlling the opening and closing of the jaws in response to the angular movement of the connecting rod 4 may be of a different construction.

What is claimed is:

1. In a bench for drawing elongated material in which the material is drawn through a die by being successively gripped by a plurality of pairs of jaws, each mounted on an individual carriage slidable upon the framework of the machine parallel to the direction of drawing, the improved drive system in which each carriage is pivotally connected to one end of an individual connecting rod the other end of which is pivotally connected to an individual rotatably mounted crank, said drive system further comprising means causing said connecting rods to impart a substantially constant linear speed to each of said carriages during a part of the movement of that carriage during which the jaws mounted on that carriage exert traction on the material being drawn, and means driving all of said cranks synchronously, with each of said cranks being angularly spaced from the next crank by the same angular distance.

2. Drawing bench as claimed in claim 1 which comprises three jaw-carrying carriages actuated by three cranks spaced apart.

3. Drawing bench as claimed in claim 1 in which each crank and connecting rod system is driven from a shaft rotating at a constant speed through a universal joint the two shafts of which are angularly spaced with respect to each other.

4. Drawing bench as claimed in claim 1 in which each connecting rod used to actuate a carriage is made in two parts pivotally connected to each other at a point which is connected by another rod to another crank driven in synchronism with the first crank.

5. Drawing bench as claimed in claim I in which the angular movement of each connecting rod with respect 7. Drawing bench as claimed in claim 6 in which said linkage comprises a composite link positioned between two articulated levers, which link may be elongated by compressing a spring, one of the ends of said link being axially slidable in its point of attachment to one of the levers. 

1. In a bench for drawing elongated material in which the material is drawn through a die by being successively gripped by a plurality of pairs of jaws, each mounted on an individual carriage slidable upon the framework of the machine parallel to the direction of drawing, the improved drive system in which each carriage is pivotally connected to one end of an individual connecting rod the other end of which is pivotally connected to an individual rotatably mounted crank, said drive system further comprising means causing said connecting rods to impart a substantially constant linear speed to each of said carriages during a part of the movement of that carriage during which the jaws mounted on that carriage exert traction on the material being drawn, and means driving all of said cranks synchronously, with each of said cranks being angularly spaced from the next crank by the same angular distance.
 2. Drawing bench as claimed in claim 1 which comprises three jaw-carrying carriages actuated by three cranks spaced 120* apart.
 3. Drawing bench as claimed in claim 1 in which each crank and connecting rod system is driven from a shaft rotating at a constant speed through a universal joint the two shafts of which are angularly spaced with respect to each other.
 4. Drawing bench as claimed in claim 1 in which each connecting rod used to actuate a carriage is made in two parts pivotally connected to each other at a point which is connected by another rod to another crank driven in synchronism with the first crank.
 5. Drawing bench as claimed in claim 1 in which the angular movement of each connecting rod with respect to the carriage which it actuates causes the automatic opening and closing of the jaws on that carriage which grip the product to be drawn.
 6. Drawing bench as claimed in claim 5 in which there is a crankpin fixed to each connecting rod at the point of its articulation to its carriage, which crankpin actuates linkage controlling the movements of the jaws with respect to the carriage.
 7. Drawing bench as claimed in claim 6 in which said linkage comprises a composite link positioned between two articulated levers, which link may be elongated by compressing a spring, one of the ends of said link being axially slidable in its point of attachment to one of the levers. 